Access time sensitivity analysis for hard disk drives.

摘要

Data access time is an important performance measure of any mass data storage system. It is the time between a data request received by the data storage system and the last bit of requested data sent to the host. For a magnetic hard disk drive, its data access time depends on many factors: how fast the actuator moves from tracks to tracks, the rotational speed of the platter, the size of the buffer for storing requests and data, and the algorithm that schedules the data requests. A part of the data access time in a magnetic HDD is the time elapsed from the start of track seeking to the end of data transfer. This thesis considers a number of physical disk parameters that impact this part of the data access time to derive the direct analytical relations between the access time and the disk parameters. Based on the analytical relations, detail sensitivity researches of physical access time on disk parameters and request spatial distributions have been studied both analytically and numerically. Four simulation tools have been developed for the studies of servo system, impact of disk parameters on access time, relations between access time distribution and request spatial distributions, and scheduling algorithms.